Hygrothermal load compensating structures in an integrated lead suspension

ABSTRACT

An integrated lead disk drive suspension including a load beam and one or more conductive leads. The load beam has a mounting region on a proximal end, a head bonding platform on a distal end, and one or more spring regions connecting the head bonding platform to the mounting region. The conductive leads are integrated with and insulated from the load beam by an adhesive dielectric layer, and extend between the head bonding platform and the mounting region. The leads are adapted to reduce mechanical effects of the leads and/or dielectric layer on spring characteristics of the spring regions. One embodiment of the leads includes at least a first compensating portion which extends off the load beam and traverses a nonlinear path around at least a portion of one or more of the spring regions. In another embodiment the portions of the conductive leads extending between the distal end of the load beam and the head bonding platform are substantially free from the dielectric layer. In yet another embodiment the width of portions of the dielectric layer is about equal to or less than the width of adjacent portions of the conductive leads.

This is a continuation of U.S. patent application Ser. No. 08/249,117,filed May 25, 1994, entitled "LAMINATED STRUCTURES FOR A DISK DRIVESUSPENSION ASSEMBLY", which is a continuation-in-part of U.S. Pat. No.5,491,597 issued on Feb. 13, 1996 and entitled "GIMBAL FLEXURE ANDELECTRICAL INTERCONNECT ASSEMBLY" and a continuation-in-part of commonlyassigned U.S. patent application Ser. No. 08/227,978 filed Apr. 15, 1994and entitled "ELECTRICAL TRACE INTERCONNECT ASSEMBLY" now abandoned andrefiled as a file wrapper continuation, Ser. No. 08/674,342, entitled"MAGNETIC HEAD SUSPENSION WITH SINGLE LAYER PRE-SHAPED TRACEINTERCONNECT".

BACKGROUND OF THE INVENTION

Suspension assemblies are spring structures in disk drives that positiona read/write head assembly nanometers away from the rapidly spinningsurface of a rotatable disk or other data storage device. The suspensionassembly presses the head toward the disk surface with a precise forceapplied in a precisely determined location. The head assembly "flies"over the irregular (at this scale) surface of the disk at a heightestablished by the equilibrium of the suspension assembly downward forceand the increasing lift force of the air stream generated by thespinning disk as the head nears the disk.

A head suspension assembly (HSA) includes the suspension assembly, thehead assembly, and an interconnect assembly. The interconnect assemblyis a collection of transmission elements designed to transmit data toand from the head assembly. HSAs are used in magnetic hard disk drives,the most common today, or other type of drives such as optical diskdrives.

The suspension assembly includes two spring structures, a load beam anda gimbal, each a carefully balanced combination of rigid regions andflexible spring regions. The load beam is a resilient spring platedesigned to provide lateral stiffness and calibrated to apply thenecessary load on the head assembly. The gimbal is a spring positionedat the distal end of the suspension assembly and of the load beam. Thegimbal holds the head assembly at an appropriate orientation (flyingattitude) and at a constant distance over the contours of the disk, evenif the load beam flexes and twists. The head assembly is attached to thegimbal and includes a "head," a highly sensitive read/write transducer,attached to an air bearing slider. The head assembly also includeselectrical terminals configured for interconnection to the interconnectassembly for receiving and relaying data (read and write signals).

A magnetic write transducer transforms electrical write signals intosmall magnetic fields. The magnetic field magnetize patterns on amagnetic disk. The order of the magnetic fields and their subsequentorientation defines a bit code representing the stored data. A magneticread transducer "reads" these magnetic fields as it flies over them andconverts them back into electrical signals.

The suspension assembly can be attached at its proximal end to a rigidarm or directly to a linear or rotary motion actuator. The actuatorrapidly moves (and then abruptly stops) the HSA over any position on aradius of the disk. The radial HSA movement and the rotation of the diskallow the head to quickly reach every location above the disc. The rapidstop and go movement causes very high stresses on the HSA.

The closer the head assembly can fly to the surface of a magnetic disk,the more densely information can be stored (the strength of a magneticfield varies proportionally to the square of the flying distance, thusthe smaller the head's flying clearance the smaller the magnetic "spot"of information). Manufacturers of disk drives strive to reach flyingclearances close to 100 nanometers=0.1 micrometers (a human hair isabout 100 micrometers thick). However, the head assembly must not touchthe disk ("crash"), since the impact with the spinning disk (rotating atabout 3600 rpm or faster) can destroy both the head, the surface of thedisk, and the stored data.

Amplifying and control electronic circuits process, send, and receivethe data signals to and from the head assembly. Signal transmissionrequires conductors between the dynamic "flying" head and the circuitry.Traditional head assemblies complete a read/write circuit loop with twoconductors, usually copper wires encapsulated in a plastic sheeting.Newer magneto-resistance head assemblies require four or moreindependent conductors. The interconnect assembly includes theconductors and accompanying insulators and connectors.

Designers and manufacturers of HSAs face competing and limiting designconsiderations. During operation, the suspension assembly should be freeof unpredictable loads and biases which alter the exact positioning ofthe head assembly. The suspension assembly should respondinstantaneously to variations in the surface topology of a disk.Alterations to the flying height of the head can significantly affectdata density and accuracy and even destroy the system in a crash.

Rigidity and stiffness increase in relation to the third power ofcross-sectional thickness. To respond to air stream changes and to holdthe flying head at the appropriate orientation, suspension assembliesare very thin and flexible, specially around the sensitive spring andgimbal areas. Interconnect assembly conductors have a large effect onsuspension assembly performance. Conductor stiffness alone greatlyaffects the rigidity of the spring regions and flight performance. Astandard conductor placed atop of a thin suspension can more than doublea spring region's stiffness and detract from the ability of the springregion to adjust to variations in the surface of the disk, vibrations,and movement. The effect of the conductors on a gimbal region, thethinnest and most delicate spring in the suspension assembly, is evenmore pronounced. Conductors placed over spring regions must notplastically deform (become permanently bent) when the spring regionsflex, since such deformation hinders the return of the spring to itsnormal position and applies a load on the suspension assembly.

The ideal HSA comprises components low in mass. Excessive inertialmomentum caused by excessive mass can cause overshoot errors. Overshooterrors occur when momentum carries the whole HSA past the intendedstopping point during positioning movement. Low-in-mass HSAs are alsoeasier to move, resulting in power savings in multiple platter diskdrives.

The manufacture of HSAs, like that of any commercial product, must beefficient. Reduction of manufacturing steps is desired. Damaged ormisaligned components introduce biases and loads and drasticallydiminish the manufacturing useful output yield. Complex shaping andmounting processes are costly and decrease the reliability of the wholeHSA manufacturing process.

To avoid defects and unpredictable loads and biases, exacting tolerancesare necessary. During the HSA manufacturing and assembling process, thebuildup of deviations from tolerance limits causes planar deviationsthat can affect the flying attitude of the head assembly. The parametersof static roll and static pitch torque in the final HSA result fromthese inherent manufacturing and assembly tolerance buildups.

Mounting and placement of current interconnect assemblies is usuallydone by hand. Hand mounting is imprecise and costly. Precise conductorplacement is specially critical in the delicate gimbal region. As theindustry transitions to smaller slider/transducer sizes to increase datastorage density, limitations of the current interconnecting devicesincrease the potential for read/write errors and impose ceilings on datastorage density.

Using current interconnect technology, workers bond two to five lengthsof wire to the head assembly, using fixturing to manage the wires whileadhesively bonding the head assembly to a stainless steel suspension.Next, the lengths of wire are shaped by hand, using tweezers and toolingassistance to form a service loop between the head assembly and thesuspension assembly and to position the wire along a predetermined wirepath on the suspension assembly. The wires are tacked to the suspensionusing adhesive or wire capture features formed into the suspension.Special care is taken to avoid pulling the service loop too tight orleft too loose. A tight service loop places an unwanted torque on theslider causing flying attitude errors. Loose service loops allow thewire to sag down and scrape on the spinning disk. Both conditions arecatastrophic to drive performance. Through-out the process of handlingthe slider and wires there is a risk of damaging the wires or thedelicate load beam and gimbal. Load beams or gimbals accidentally bentduring the manufacturing operations are scrapped. Often the headassembly also cannot be recovered, adding additional losses to the scrappile.

Another type of suspension assembly interconnect utilizes plasticcompounds acting as integral spring elements in the suspension assembly.Use of plastic materials as spring elements in load beam and gimbalconstruction presents performance problems since plastic materials donot possess optimal mechanical spring qualities. As the flying heightand head size continually decrease in the progression towards greaterdisk storage density, the accuracy and control needed to align thetransducer to the correct data track upon the disk surface becomes morecritical.

During operating conditions the drive temperature operating ranges canspan 80 degrees Celsius. Plastics expand and contract more than metalsduring temperature changes. The use of thermally expansive plastics asprincipal spring structural elements of the load beam or gimbal regionaffects the dimensional stability of the suspension assembly. Theexpansion and contraction of integral plastic spring elements introducesloads and stresses on the metal components. Additionally, because oftheir mechanical characteristics, integral plastic spring elementstraditionally only have been used in suspension assemblies that resistthe pull of negative pressure sliders, sliders that create a vacuum thatpulls them toward the disk.

SUMMARY

The present invention is new laminate structures for use in headsuspension assemblies (HSAs) and a method to manufacture the laminatestructures. The present laminate structures eliminate manual handling ofconductors by integrating the manufacture of the interconnect assemblywith that of the suspension assembly. Reduction in handling minimizeshandling damage, thereby reducing damaged components and increasingmanufacturing yields. Since the suspension assembly and the interconnectassembly are manufactured together, the variability of the alignment ofthe component (standard deviation) is minimal. Errors during mechanicalperformance are therefore reduced. Conductor geometry is always preciseand no expensive and time-consuming manual fixturing during assembly isrequired. Less handling, less bent parts, and less assembly errorsresult in a more consistent fly height performance and more efficientmanufacturing process.

The first step in the manufacture of the laminate structures is toproviding a multi-layer laminate sheet. The sheet comprises a firstlayer of a metal spring material, an intermediate second layer of anelectrically insulating, preferably adhesive, material, and a thirdlayer of an electrically conductive material. The second layer onlyprovides minimal spring characteristics to the laminate structure as awhole. The third layer can be a conductive spring material such asberyllium copper.

The second step is to form the layers, starting from the outside in. Amethod of forming is chemical or plasma etching. The first layer isformed into a spring element. The third layer is formed into at leastone trace, the trace including at least one elongated conductorconfigured for electrical coupling to a head assembly. The secondelement is formed into panels shaped as the areas of contact between theelements of the first and the third layer.

To complete manufacture of a head suspension assembly (HSA), the tracesof the laminate structure are electrically coupled to a head assemblyand the laminate structure is attached to other elements of the HSA.

Laminate structure embodiments include interconnect assemblies,interconnect-suspension assemblies, and gimbal-interconnect assemblies.Interconnect assemblies attach to a load beam and include at least oneconductive trace. The second layer provides dielectric insulation andthe third layer can include support and stiffening plates.

Interconnect-suspension assemblies include an interconnect assembly anda suspension assembly including a gimbal and a load beam having a rigidregion and a spring region. The gimbal can be formed out of the firstlayer, the third layer, or both. The spring region of the load beam canalso be formed out of either or both layers.

A interconnect-suspension assembly embodiment has a first layer ofstainless steel, a thin second layer of polyimide, and a third layer ofberyllium copper. The first layer has a planar load beam plate includinga rigid region. The third layer has at least one trace for electricalcoupling to the head assembly, each trace including a gimbal region at adistal end portion and a load beam region at a proximal end portion. Thegimbal region is shaped as a gimbal spring arm. The second layer has atleast one panel, the panels placed in between overlapping areas of thefirst layer and of the third layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a head suspension assembly in accordancewith the present invention.

FIG. 2 is a detail enlarged view of the gimbal of the head suspensionassembly shown in FIG. 1.

FIG. 3 is a perspective view of a three-layer sheet of laminate materialused to manufacture laminate structures in accordance with the presentinvention.

FIG. 4 is a perspective view of one side of the three-layer sheet shownin FIG. 3 after the stainless steel layer has been etched into a loadbeam.

FIG. 5 is a perspective view of the other side of the three-layer sheetshown in FIG. 3 after the beryllium copper layer has been etched into atraces for a gimbal-interconnect assembly.

FIG. 6 is an exploded perspective view of the suspension assembly shownin FIG. 1 manufactured from the three-layer sheet shown in FIG. 3wherein the exposed areas of the second layer have been etched away.

FIG. 7 is a perspective view of a second embodiment of a head suspensionassembly in accordance with the present invention, the load beamincluding stiffening side rails.

FIG. 8 is an exploded perspective view of the head suspension assemblyshown in FIG. 7 including the three-layer suspension assembly, the headassembly, and the supporting base plate.

FIG. 9 is an enlarged detail perspective view of the three layers of thegimbal of the head suspension assembly shown in FIG. 7.

FIG. 10 is a perspective view of a third embodiment of a head suspensionassembly in accordance with the present invention.

FIG. 11 is an exploded perspective view of the head suspension assemblyshown in FIG. 10 including a three-layer suspension assembly, a headassembly, a supporting base plate, and a load button cover.

FIG. 12 is a perspective view of a fourth embodiment of a headsuspension assembly including a three-layer gimbal-interconnect assemblyin accordance with the present invention.

FIG. 13 is an exploded perspective view of a distal end portion of thehead suspension assembly shown in FIG. 12.

FIG. 14 is a perspective view of a fifth head suspension assemblyincluding another embodiment of a three-layer gimbal-interconnectassembly.

FIG. 15 is an exploded perspective view of the head suspension assemblyof FIG. 14.

FIG. 16 is an exploded perspective view of a distal end portion of asixth embodiment of a head suspension assembly including anotherembodiment of a three-layer gimbal-interconnect assembly wherein theorder of the layer is reversed.

FIG. 17 is a perspective view of a seventh embodiment of an HSA inaccordance with the present invention wherein the traces extend over thespring aperture of the load beam.

FIG. 18 is a perspective view of an eighth embodiment of an HSA inaccordance with the present invention wherein the traces extendalongside the spring region of the load beam.

FIG. 19 is a perspective view of a ninth embodiment of an HSA inaccordance with the present invention wherein the traces act as thespring elements of the spring region.

FIG. 20 is a perspective view of a tenth embodiment of an HSA inaccordance with the present invention including spring support plates.

FIG. 21 is an enlarged detail perspective view of vertically mountedhead electrical terminals electrically coupling to traces of agimbal-interconnect assembly.

FIG. 22 is an enlarged detail perspective view of another method ofcoupling horizontally mounted head electrical terminals electrically totraces of a gimbal-interconnect assembly.

FIG. 23 is an enlarged detail perspective view of another method ofcoupling the vertically mounted head electrical terminals electricallyto traces of a gimbal-interconnect assembly.

FIG. 24 is a side view of a cross-sectional cut along the longitudinalaxis of a head assembly attaching to the suspension assembly of FIGS. 10and 11 wherein the slider is electrically coupled to the first layer bya dot of conductive epoxy.

FIG. 25 is a side view of a cross-sectional cut along the longitudinalaxis of the head assembly attaching to the suspension assembly of FIGS.10 and 11 wherein the first layer and the second layer are etched sothat a bond pad in the third layer is electrically coupled to the loadbutton of the load button cover.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a HSA 12 manufactured in accordance with the presentinvention aligned with longitudinal axis 18. HSA 12 includes aninterconnect-suspension assembly 14 and a head assembly 20 attached to adistal end of the interconnect-suspension assembly 14.Interconnect-suspension assembly 14 comprises a load beam 32 (betterseen in FIG. 4), an interconnect assembly 15, and a gimbal 40. Load beam32 includes a proximal end 33, a distal end 34, a base region 35 at theproximal end 33, a rigid region 37 at the distal end 34, and a springregion 36 in between base region 35 and rigid region 37. Spring region36 has a spring aperture 38 used to tailor the stiffness of the springregion 36.

Interconnect assembly 15 comprises four traces 71 extending the lengthof the load beam 32, insulation panels 92 and 93 shown in FIG. 6, andconnector means shown in FIGS. 21-23 (other embodiments can includeconnector means known in the art). Traces 71 are elongated and resilientpre-patterned electrical conductors that connect the head assembly 20 toamplifying and control electronics (not shown). The traces 71 include aproximal end 73, a distal end 74, a load beam region 72 adjacent theproximal end 73, and a gimbal region 80 adjacent the distal end 74. Thewidth and the thickness of traces 71 can change at different regions toaffect stiffness or to change the electrical resistance.

The load beam region 72 of traces 71 includes a proximal base region 75,a middle spring region 76, and a distal rigid region 77. In the presentembodiment, the gimbal regions 80 of traces 71 are shaped as elements ofgimbal 40. The excellent mechanical and electrical properties of BeCuallow the third layer 70 to act not only as an interconnect assembly,but also as a spring element. The present interconnect assembly 15 actsas both an interconnect assembly and as a gimbal, and is therefore agimbal-interconnect assembly.

In the present embodiment, the rigid regions 77 of the traces 71 alsoact as stiffening rails that give added rigidity to the rigid region 37of the interconnect-suspension assembly 14 to modify the resonanceresponse of the interconnect-suspension assembly. The thickness and/orwidth of the rigid region 77 of the traces 71 can be increased toincrease their stiffness. In FIG. 1, the traces 71 only extend slightlypast the proximal end 33 of the HSA 12. The traces 71 can extend all theway back to amplifying and processing circuitry placed on the actuatorarm (not shown) or on the frame of the disk drive (also not shown).

FIG. 2 shows a detail enlarged view of gimbal 40. Gimbal 40 providesgimballing support to the head assembly 20, that is, maintaining thehead assembly 20 correctly oriented and equidistant to the rotatingdisk, regardless of the movements and twists experienced by the loadbeam 32 during actuator motion. Gimbal 40 includes longitudinal springarms 42 suspending a platform 44 over an aperture 41 on the load beam32. Platform 44 has a frame 45 encircling two bond pads 46 suspended bylateral spring arms 43.

Head assembly 20 includes an air-bearing slider 21, a read/writetransducer 22 attached to the slider 21, and electrical terminals 23,better seen in FIG. 21, for electrically coupling to the transducer 22.The slider 21 is attached by conductive epoxy to bond pads 86 of thegimbal region 80 of the traces 71.

The first step in the manufacture of laminate structures in accordancewith the present invention is to provide a multi-layer laminate sheet 10such as the one illustrated in FIG. 3. The sheet 10 has three layers, afirst layer 50, a middle second layer 90, and a third layer 70. Otherlaminate structure embodiments not shown can be manufactured out ofsheets with more layers.

The first layer 50 is about 63.5 micrometers-thick and will typicallyrange from 20 to 90 micrometers in other embodiments. In the drawings,elements of the first layer 50 are numbered between 50 to 69. Firstlayer 50 is a sheet of 1.14 gigapascal yield strength and 1.31gigapascal tensile strength stainless steel, a metal spring material.Other spring materials can also be used. Spring materials are those thatdo not plastically deform (yield) under the most extreme loads appliedduring HSA use.

The second layer 90 is a thin 25 micrometers thick sheet of epoxy, anadhesive and dielectric or insulating material. The second layer 90joins and insulates the fist layer 50 and the third layer 70. The secondlayer 90 provides only minimal spring characteristics to the wholelaminate structure in comparison to the first layer 50 and the thirdlayer 70. The second layer 90 will typically range from 5 to 60micrometers in other embodiments. Other embodiments, shown in FIGS. 7-9,use thermoplastic polyimide. Ideal materials for the second layer 90have good electrical characteristics--low dielectric constant, highdielectric resistance, and high dielectric strength. To prevent shift orshear (lateral sliding of the layers with respect to each other) and toassure mechanical stability through time and temperature cycles, thesecond layer 90 optimally has a high elastic modulus and a temperaturecoefficient closely matching that of the first layer 50 and that of thethird layer 70. In still other embodiments, the second layer 90 does notact as an adhesive, and additional adhesive layers are added to attachfirst layer 50 and third layer 70. Elements of the second layer 90 arenumbered 90 to 99.

The third layer 70 is about 25 micrometers thick and will typicallyrange from 10 to 90 micrometers thick in other embodiments. Elements ofthe third layer 70 are numbered between 70 to 89. In the presentembodiment, the third layer 70 is a sheet of beryllium copper UNSC 17200(BeCu), a conductive metal spring material with a yield strength ofabout 1.24 gigapascals and a tensile strength of about 1.31 gigapascals.Other embodiments include other conductive spring materials. Still otherembodiments, where the third layer 70 is not used as a spring layer, usenon-spring conductive materials.

The second step in the manufacture of laminated structures is to formand pattern the two outside metal layers, first layer 50 and third layer70, into elements for the desired laminate structure. Forming can beaccomplished by chemical etching or other methods known in the art suchas electro-discharge machining (EDM). Both the first layer 50 and thethird layer 70 can be chemically etched in a variety of continuous ordiscontinuous patterns using common etchants such as ferric chloride.Either the first layer 50 or the third layer 70 can be etched first.Layers 50 and 70 can even be etched simultaneously. Laminateconstruction allows manufacturing using materials that are thinner thanthose normally capable of being processed. The second layer 90 supportsthe metal layers 50 and 70 throughout the etching process and allowshigher manufacturing yields of components with fragile and/ordiscontinuous geometries.

FIG. 4 shows the result of the step of etching the first layer 50 ofsheet 10 into elements for the HSA 12 of FIG. 1. The etching processexposes areas 91A of the second layer 90 not overlapped by elements ofthe first layer 50. The thickness of layer 50 is greatly exaggerated tobetter illustrate the relief etching. One step double-sided exposure inan etching process with multi-step etching provides tight alignment oftop and bottom features. Multiple step exposure also can be used topartially etch the first layer 50 or the third layer 90.

FIG. 5 shows the result of the step of etching the third layer 70 aselements of the interconnect assembly of the HSA 12 of FIG. 1. Etchingof the third layer 70 again exposes areas 91B of the second layer 90 notoverlapped by elements of the third layer 70. The thickness of the fourtraces 71 is exaggerated to accentuate the relief etching. The traces 71are electrically isolated from each other. Separation between the traces71 is controlled by the etching process and maintained by the secondlayer 90.

The second layer 90 acts as a hard stop during the chemical etching ofthe metal layers 50 and 70. The intervening second layer 90 allows eachmetal layer 50 and 70 to have a different geometry. The BeCu third layer70 can be etched with cupric chloride to avoid a masking step on thestainless steel first layer 50 of the laminate sheet 10.

The third step in the manufacture of laminate structures comprisesplasma etching the second layer 90. The second layer 90 can be shapedusing other methods known in the art such as chemical etching or lasercutting. The first layer 50 and third layer 70 can act as metal etchingmasks during the etching of the second layer 90. FIG. 6 shows the secondlayer 90 etched into a plurality of panels 92 and 93. The panels 92 and93 are etched to allow elements of the first layer 50 and of the thirdlayer 70 to act as the main spring elements of the HSA 12. To free thespring elements of the first layer 50 and/or the third layer 70 and toreduce stiffness and mass, all exposed areas 91 of the second layer 90,that is all areas not overlapped by both the first layer 50 and thethird layer 70, and thus not used for insulation or for bonding, havebeen etched away. The exposed areas 91 are excess material. However, amanufacturer can choose various times along the HSA 12 manufacturingprocess at which to etch-away the exposed areas 91 and remove the excessmaterial. The excess material helps the second layer 90 to act as abacking support to prevent handling damage. The etched first layer 50,second layer 90, and third layer 70 together form theinterconnect/suspension assembly 14.

A fourth manufacturing step can comprise plating selected areas of thefirst layer 50 and the third layer 70. To improve terminal contactsplating nickel, gold, silver, tin, etc. can be applied on connectorsites of the third layer 70, such as the proximal end 73 and the distalend 74. The second layer 90 also acts as an insulator duringelectroplating processes. Plating or other passivation is also useful toprotect the entire third layer 70 from corrosion.

The fifth and final step in the manufacture of HSA 12 is to attach theinterconnect/suspension assembly 14 to all other elements. FIG. 6 showsan exploded view of the head suspension assembly (HSA) 12, including thehead assembly 20 and a supporting base plate 95. The etched layers 50,70, and 90 create the interconnect/suspension assembly 14. Explodedviews are shown merely for illustration purposes. Since laminatestructures are etched directly out of laminate sheet 10, the differentetched layers 50, 70, and 90 are not separated during manufacturing oroperation. All elements of a same layer are co-planar when initiallyetched, however, forming operations may be included in later steps.

Only the first layer 50 and the third layer 70 include structural springelements. First layer 50 includes a load beam plate 52 and a gimbalplatform 64. Load beam plate 52 is a wedge-shaped spring member alignedalong the longitudinal axis 18 and includes a proximal end 53, a distalend 54, a base region 55 adjacent to the proximal end 53, a springregion 56 contiguous to the base region 55, a rigid region 57 contiguousto spring region 56, and a gimbal region 60 which is adjacent to thedistal end 54. The rigid region 57 includes a tooling and alignment hole58. The gimbal region 60 has a central aperture 61. The gimbal platform64 rests in the middle of aperture 61.

Third layer 70 includes the four traces 71. The spring region 76 and therigid region 77 match the outer outline of the corresponding springregion 56 and rigid region 57 of the underlying load beam plate 52 ofthe first layer 50. The gimbal region 80 of each trace 71 of the thirdlayer 70 is configured as a portion of the gimbal 40 and includes alongitudinal spring arm region 82, a lateral spring arm region 83, thatbroadens into a horizontal bond pad 86. The spring arm regions 82 and 83and bond pads 86 form a platform 85 that partially matches the platform64 of the first layer 50. In other embodiments (not shown), the thirdlayer 70 can also be shaped only as an interconnect assembly and performno gimballing functions.

The second layer 90 includes small gimbal panels 92 and trace insulationpanels 93. The gimbal panels 92 insulate, separate, and join the gimbalregion 80 of the traces 71 to the platform 64 of the first layer 50. Thetrace panels 93 extend underneath traces 71 and insulate the traces 71from the load beam plate 52. Although a support element duringmanufacture, the second layer 90 does not act as a spring or hingeelement during operation of the HSA 12.

The use of metal spring elements minimizes the dimensional stabilityconcerns that afflict laminate structures that use a plastic springelement. The panels 92 and 93 act as insulators, as bonding agents, andas dampers that reduce vibration and settling times (time needed for theHSA 12 to settle after rapid positional movement). Additional servicepanels can be added to increase damping characteristics.

FIGS. 7 and 8 show a HSA 112 including elements similar to the elementsof HSA 12 of FIG. 1. Elements in all embodiments are identified by thesame last two numbers as used for similar elements of HSA 12. Anadditional first number is used to refer to the HSA embodiment shown.HSA 112 includes a an interconnect-suspension assembly 114 having agimbal 140 and a load beam 132 with side rails 139.Interconnect-suspension assembly 114 includes a first layer 150, asecond layer 190, and a third layer 170.

In the present embodiment, side rails 139 are formed by manufacturing aload beam plate 152 out of the first layer 150. The load beam plate 152can be reinforced or even replaced by plates from the third layer 170and the second layer 190. Load beam plate 152 includes a gimbal region160 and a rigid region 157. Load beam plate 152 includes small wingsprojecting along longitudinal edges of the rigid region 157 of the loadbeam plate 152 of the first layer 150. The wings are bent generallyperpendicularly to the surface of the load beam plate 152 to form theside rails 139.

Traces 171 are etched out of the third layer 170. The traces 171 haverigid region 177 that also reinforces the rigid region 157 of load beamplate 152.

FIG. 9 shows an enlarged exploded detail of the gimbal 140 of the HSA112. In this embodiment, the first layer 150 and the third layer 170compliment and support each other to together create the gimbal 140. Inother embodiments, either third layer 170 (embodiment of FIG. 1) orfirst layer 150 (embodiment not shown) can be the principal gimbalspring elements. Although only a few gimbal embodiments are shown in thedrawings, the first layer 150 and the third layers 170 can be etchedinto almost any gimbal design known in the art.

In the present embodiment, the load beam plate 152 of the first layer150 has longitudinal arms 162 that suspend a gimbal platform 164 in themiddle of an aperture 161 in the gimbal region 160 of load beam plate152. The platform 164 includes two mechanical bond pads 166 attachedinside of frame 165 by lateral spring arms 163.

The longitudinal spring arms 162 and the lateral spring arms 163 of thefirst layer 150 compliment straddling longitudinal spring arms 182 andlateral spring arms 183 of the third layer 170. The first layer arms 162and 163 and the third layer arms 182 and 183 do not overlap, thuscreating thin and very responsive one-layer thick spring elements. Thetraces 171 of the third layer 170 end in bond pads 186 that are placedover the bond pads 166 of the first layer 150 and match their outline.Panels 192 and 193 of the second layer 190 insulate, separate, andadhesively bond the elements of the first layer 150 and the elements ofthe third layer 170.

FIGS. 10 and 11 show a HSA 212 wherein first layer 250 includes a loadbeam plate 252 truncated at the end of rigid region 257 and a separate"T" shaped gimbal tongue 264. The tongue 264 acts as a base gimbalplatform for mounting a head assembly 220. The second layer 290 includestrace pads 293 and gimbal pads 292 separating, joining, and insulatingthe elements of the first layer 250 and the elements of the third layer270. The third layer 270 includes traces 271 and a single widehorizontal bond pad 286 that matches and attaches, through a secondlayer panel 292, to a proximal portion of the tongue 264 of the firstlayer 250.

The tongue 264 is supported by spring arms 282 of a gimbal portion 280of traces 271. The gimbal portion 280 is formed or rolled according tomethods known in the art to achieve slider offset, that is verticalseparation so that the head assembly 220 may move freely. The springarms 282 extend past the distal end of the truncated load beam 252 andrun along both sides of the bond pad 286. At the distal end of the bondpad 286, the arms 282 loop 180 degrees and end adjacent the bond pad286. Head assembly 220 is attached to bond pad 286 and is electricallycoupled to traces 271.

FIG. 11 shows an exploded view of the HSA 212 of FIG. 10. The T-tongue264 and the bond pad 286 can be seen more clearly. A supporting baseplate 295 attaches to a base region 255 of the load beam plate 252. Anew element, a load button cover 296, attaches to rigid region 257 ofthe load beam plate 252. Load button cover 296 is a triangle-shapedstainless steel plate including a pivoting gimbal load button 297 and analignment hole 298. Cover 296 attaches to the bottom surface of loadbeam plate 252. Alignment hole 298 aligns with hole 258 of the load beamplate. Load button 297 is a protruding dimple.

FIG. 12 shows a HSA 312 including a load beam 332 and a new laminatestructure, a gimbal-interconnect assembly 316 attached to the load beam332. Only the gimbal-interconnect assembly 316 is a laminate structure.

The different laminate layers of the gimbal-interconnect assembly 316are better seen in the exploded view of FIG. 13. The gimbal-interconnectassembly 316 includes a first stainless steel layer 350, a secondintermediate insulation layer 390, and a third BeCu layer 370.

The first layer 350 is attached to one side of the second layer 390 andcomprises a load beam plate 352, a flexure tongue plate 364, and aplurality of support islands 351 adjacent to the flexure tongue plate364. Support islands 351 are small, usually rectangular, plates ofstainless steel that give support and lateral stiffness to otherwiseunsupported spans of traces 371, specially during offset forming.

During offset forming a slope region 384 is created on the spring arms382 of the traces 371. The first layer 350 and the second layer 390 areremoved along the slope region 384. The slope region 384 is angled awayfrom the surface of the load beam 332, resulting in added clearance fromthe longitudinal side portions of the spring arms 382 of the traces 371during movement of the head assembly 320. The islands 351 are placed atthe ends of the slope region 384 and provide a flat support surface forpunch shaping processes during offset forming. During punch shaping, thetraces 371 are bent with a punch press. Because the punch shapingprocess may bend corners (especially the inside corners) of the sloperegion 384 of the traces 371 over the stainless steel islands 351, theislands 351 are electrically isolated from each other to preventelectrical short circuits.

The third layer 370 is attached to the other side of the second layer390 and comprises a flexure bond pad 386, two pairs of generallyparallel traces 371 that extend on the outside of thegimbal-interconnect assembly 316. The bond pad 386 can be etched at fullthickness, thus leaving a raised surface that matches the raised slope384 achieved by offset forming. The traces 371 include a proximal end373, a distal end 374, and a gimbal region 380. The gimbal region 380has a portion shaped as gimbal spring arms 382. The traces 371 act as alink between the load beam plate 352, the flexure tongue plate 364, andthe islands 351 of the first layer 350. The spring arms 382 first extendlongitudinally past the load beam plate 352 of the first layer 350 andalongside the flexure tongue 364. The arms 382 then describe twoadjacent inside "U" loops to place the distal ends 374 of the traces 371next to electrical terminals 323 of head assembly 320.

The second layer 390 comprises a plurality of intermediate insulatingpanels 392 and 393 separating, but also bonding, all overlapping areasbetween the first layer 350 and the third layer 370.

The method of manufacture of the HSA 312 including gimbal-interconnectassembly 316 is similar to that of other laminate structures in thepresent invention. A three-layer laminate plate such as that of FIG. 3is provided. First, the metal layers 350 and 370 are etched into thedesired shapes, exposing areas of the second layer 390. In multi-elementdesigns such as the present gimbal-interconnect 316, the second layer390 not only acts as an etching stop, but also acts as a support sheetto hold together all the separate elements during manufacture. Second,the second layer 390 is etched. Removal of the exposed areas of thesecond layer 390 allows gimbal 340 to flex freely and reduces the massand stiffness of the gimbal-interconnect assembly 316. The metal layers350 and 370, with their superior mechanical characteristics, act as theprincipal spring elements. Third, the finished gimbal-interconnectassembly 316 is attached to load beam 332 using a weld point or othermethods known in the art. The load beam 332 includes a load button 397adjacent the distal end that is aligned with the tongue plate 364 andwith the bond pad 386. Fourth, the head assembly 320 and thegimbal-interconnect assembly 316 are mechanically coupled, usingconductive epoxy or other methods known in the art, and electricallycoupled using connector means, such as those shown in FIGS. 21-23.Conventional lead wires or other conductive traces (not shown) cancouple the traces 371 to amplifying and control electronics (not shown).The order of steps three and four can be reversed.

HSA 412 shown in FIGS. 14 and 15, closely resembles HSA 312 of FIG. 12.The main difference is that gimbal-interconnect assembly 416 includestraces 471 that extend the length of load beam 432 and past the proximalend 433 of the load beam 432. The third layer 470 has four traces 471split into two independent pairs. Traces 471 include a proximal end 473,a distal end 474 load beam region 472, a spring region 476, a rigidregion 477, and a gimbal region 480. The stainless steel layer 450 actsas a support structure and comprises a load beam panel 452, a base panel455, two spring region islands 456, a tongue panel 464, and eight gimbalarm islands 460. The stainless steel layer 450 is removed along most ofthe path of gimbal spring arms 482 and over most of the spring region436 of the load beam 432 to reduce stiffness. The stainless steelislands 456 and 460 support the traces 471 across open gaps and duringoffset forming. Gimbal arm islands 460 provide clamping locations usedto hold the spring arm 482 flat while the offset is formed. The islands460 and 456 also help with lateral stiffness, a performancecharacteristic needed on good suspension designs.

FIG. 16 shows a distal end portion of a sixth embodiment of an HSA 512including a gimbal-interconnect assembly 516 attaching to a rigid region537 of a load beam 532. Gimbal-interconnect 516 is a laminate structurewherein the order of the layers with respect to the load beam 532 isreversed when compared to the embodiment of FIGS. 12 and 13. The firstlayer 550 includes a load beam stiffening plate 552, a tongue plate 564,and gimbal islands 560. The second layer 590 includes a plurality ofinsulation panels 592. The third layer 570 includes four traces 571acting as spring arms and two bond pads 586. A distal portion of thetraces 571 extends past the distal end of the load beam 532. The secondlayer panels 592 attach the third layer elements to the tongue plate 564of the first layer 550. The load beam plate 552 attaches to the loadbeam 532, by welding or other methods known in the art.

Conductors can affect the flexibility of the spring region of the loadbeam. A third power increase in stiffness results from increasing thethickness of the spring region by manufacturing overlapping layers. FIG.17 shows an HSA 612 including a head assembly 620, a gimbal-interconnectassembly 616, and a load beam 632. The load beam 632 includes a baseregion 635, a spring region 636, a rigid region 637, and gimbal region640. Spring region 636 includes spring aperture 638 used to tailor thespring stiffness of the spring region 636 according to the required loadcharacteristics of the head assembly 620. The gimbal-interconnectassembly includes traces 671. Traces 671 include a spring region 676, arigid region 677, and a gimbal region 680.

The design of HSA 612 avoids triple-layer thickness over the springregion 636 of the load beam 632 by taking advantage of the resiliency oftraces 671 and extending the spring region 676 of the traces 671 acrossspring aperture 638. All stainless steel material and all insulatingmaterial is removed from under the spring region 676. Since the traces671 do not overlap the spring region of load beam plate, spring region636 is only one layer thick. Since the stiffness of the spring region636 is directly proportional to the third power of its thickness, a onelayer spring region 636 has a stiffness several times lower than a threeor two layer spring region.

FIG. 18 shows another variation of the one-layer concept, in whichspring regions 776 of traces 771 are configured to extend in parallelpaths to the longitudinal axis 18 alongside spring region 736 of theload beam 732. In both the embodiment of FIG. 17 and in the presentembodiment of FIG. 18, the spring regions 676 and 776 of traces 671 and771 can be routed in an angle with respect to the longitudinal axis 18,to further reduce the stiffening vector and increase the length of thespring regions 676 and 776.

Not only can the interconnect assembly act as a gimbal (eliminating theeffect of conductor added stiffness in the gimbal), but it can alsoreplace the spring region of the load beam (.thereby also eliminatingconductor added stiffness in the spring region). FIG. 19 shows a ninthembodiment of an HSA 812 having traces 871 that widen at spring regions876 to provide all the spring material for spring region 836. Allstainless steel and all insulator material are removed from springregion 836. The first layer 850 comprises two separate plates, a loadbeam plate 852 and a base plate 855.

In some HSA embodiments that use very thin materials, such as HSA 912shown in FIG. 20, an increase in strength across the spring region isdesired to prevent metal yielding. HSA 912 includes spring regionstiffening plates 981. Stiffening plates 981 comprise third layermaterial attached to load beam plate 952 by second layer adhesivematerial. The stiffening plates 981 extend from base region 935, overthe sides of the spring region 936, and into a portion of rigid region937. In other embodiments (not shown), the stiffness of any region ofthe load beam plate 952 can be tailored by adding stiffening pads ofmatching geometries.

FIG. 21 shows an enlarged detail view of an embodiment of a connectormeans from the electrical terminals 423 of head assembly 420 to thetraces 471 of the gimbal-interconnect assembly 416 of FIG. 14.Connecting loops 448 of fine wire are first bonded to each electricalterminal 423 before the head assembly 420 is attached to thegimbal-interconnect assembly 416. The wire bonding can be done withconventional ultrasonic bonding equipment, since the two bond points 424and 425 rest on the same plane. Once the head assembly 420 is attachedto the gimbal-interconnect assembly 416, the connecting loops 448 arepushed down and electrically connected to the corresponding traces 471using methods known in the art such as wire bonding, soldering, orattachment by a conductive adhesive. Optionally, the connecting loops448 can be twisted to lay horizontally on the traces 471 to provide awider contact surface. The advantages of the connecting loops 448 areflexibility, redundant two-point (424 and 425) connections to the headterminals 423, and ease of manufacture.

FIG. 22 shows another method for connecting the traces 471 to theelectrical terminals 423 of head 420. "L" shaped contacts 449 extendfrom the side mounted electrical terminals 423 to the top of slider 421.The traces 471 then bond directly onto the contacts 449. The traces 471can also couple electrically and mechanically to the top of the slider421 when using head assemblies with top-mounted electrical terminals(not shown).

FIG. 23 shows yet another method for connecting the traces 471 to theelectrical terminals 423. Droplets 429 of conductive epoxy form anelastic electrical bond between the traces 471 and the electricalterminals 423. The droplets 429 are applied in a viscous state andsolidify after a cure cycle.

FIGS. 24 and 25 show different methods for allowing static electricitybleed-off from head assembly 220 of FIG. 10. HSAs generally use thesuspension assembly as an electrical ground. But since thegimbal-interconnect assembly 216 and the suspended head assembly 220 areelectrically isolated from the suspension assembly 214, the headassembly 220 can buildup an electrostatic charge that can dischargethrough the transducer to the disk surface or to the traces 271,affecting data or damaging the head assembly 220. In FIG. 24, a contactcavity 30 is etched on the bond pad 286 and on the intermediateinsulation panel 292. Contact cavity 30 allows the top of the slider 221to be connected to the tongue plate 264 of the stainless steel layer 250by a drop of conductive epoxy 227. In other embodiments (not shown), thedrop 227 can be replaced by other conductive means such as smallconductors, solder, or other means known in the art. The load button 297contacts the tongue plate 264 and grounds the slider 221 to the loadbeam plate 252. Epoxy layer 226 bonds the slider 21 to the bond pad 286.

In FIG. 25, contact cavity 31 is etched on the tongue plate 264 and theunderlying matching insulation/adhesion panel 292 to allow contactbetween the load button 297 and the surface of the bond pad 286 (whichis electrically isolated from traces 271). A layer of conductive epoxy228 connects the bond pad 286 to the top of the slider 221. Otherembodiments (not shown) ground the slider 221 using an additional traceconnected at one end to the slider 221 and at the other end to asuitable ground such as load beam 232, the actuator arm, or the frame ofthe disk drive.

There are many advantages to the present designs, both during operationand manufacture. First, BeCu traces offer important advantages. Due tothe use of BeCu, the present laminate structures have better mechanicalcharacteristics than traditional wire interconnect and suspensionassembly combinations. The use of the interconnect as the gimbal or asthe spring dramatically reduces the stiffness of the delicate gimbal orspring region. The high-tensile, high-yield strength BeCu approximatelymatches the strength and thermal coefficient of expansion of thestainless steel used to define the load beam. A high strength springmaterial that closely matches the spring characteristics ofstainless-steel under load greatly reduces the chance of subjecting thegimbal assembly to adverse shifts in the static attitude. Low strength,non-spring materials can easily yield during adverse handling andassembly operations, imparting unknown stresses to the suspensionassembly, which invariably lead to shifts in the nominal static attitudeof the gimbal flexure.

The resiliency of the third layer allows pre-shaping of the interconnectassembly in any design. Wire handling and wire service loops areeliminated and consistent conductor paths without loads or biases areachieved every time.

Second, the laminate gimbal-interconnect assemblies include the novel"island concept" wherein bifurcated spring arms are supported by smallstainless steel islands. The islands dramatically increase the lateralstiffness of the gimbal, while leaving pitch and roll stiffnessrelatively low. The islands also act as support structures for punchshaping processes during offset forming.

Third, the use of laminate structures allows the processing of materialsthat are thinner and more delicate than those normally capable of beingprocessed. The second layer supports the metal layers through theetching process, resulting in higher yields even with fragilegeometries. In addition, the laminate structure allows the replacementof some partial etching with "as rolled" material by laminating layersto a desired thickness. The suspension assembly can have single layersin the spring region or gimbal regions to lower stiffness and provideclearance. Differential material thicknesses are possible by combiningthe composite materials and partial etching processes. Low verticalprofiles are ideal for newer, "compact" disk drives with smalldisk-to-disk spacing.

Fourth, laminate structures have unique manufacturing advantages due totheir middle second layer. The second layer provides a built-in etchstop for the chemical etching of the metal layers. The interveningsecond layer allows a different geometry on each metal layer (the secondlayer is a hard stop for the metal etchant). Unique configurations arepossible where either or both metal layers can be discontinuous,consisting of separate and unconnected individual plates, thanks to themanufacturing support of the second layer. The second layer also acts asan insulator during the plating process. If some of the second layer isplasma etched away prior to plating, either metal layer can beselectively plated.

Fifth, although the second layer is used as a support element duringmanufacture, during operation only the better suited first and thirdlayers act as spring elements. The second layer is etched away, freeingthe metal spring structures and eliminating the concerns of dimensionalstability and unnecessary mass and stiffness found in other laminatestructures.

Sixth, the laminate gimbal-interconnect assembly has better electricalcharacteristics than the prior art. The width and thickness of thetraces can vary to change the resistance or the capacitance of theconductor along its path. There is no impedance fluctuation caused byloose wires. Traces provide improved electrical signal performance inhigh frequency operations.

The invention is not to be taken as limited to all of the detailsthereof as modifications and variations thereof may be made withoutdeparting from the spirit or scope of the invention.

What is claimed is:
 1. An integrated lead disk drive suspension,including:a load beam having proximal and distal ends, a base region onthe proximal end, a rigid region between the proximal and distal ends, ahead bonding platform on the distal end, and one or more spring regionsconnecting the head bonding platform to the base region; and one or moreconductive traces integrated with and insulated from the load beam by anadhesive dielectric layer, the traces and dielectric layer extendingbetween the head bonding platform and the base region and including oneor more compensating portions each of which extends off the load beamand traverses a nonlinear path around at least a portion of one or moreof the spring regions to reduce mechanical effects of the conductivetraces and dielectric layer on spring characteristics of the springregions.
 2. The integrated lead suspension of claim 1 wherein the one ormore spring regions include a spring region connecting the rigid regionof the load beam to the base region.
 3. The integrated lead suspensionof claim 2 wherein the one or more compensating portions include acompensating portion traversing a nonlinear path of at least about 90°around the one or more spring regions.
 4. The integrated lead suspensionof claim 2 wherein the one or more compensating portions include acompensating portion traversing a nonlinear path of at least about 180°around the one or more spring regions.
 5. The integrated lead suspensionof claim 1 wherein the one or more compensating portions include acompensating portion traversing a nonlinear path of at least about 90°around the one or more spring regions.
 6. The integrated lead suspensionof claim 1 wherein the one or more compensating portions include acompensating portion traversing a nonlinear path of at least about 180°around the one or more spring regions.
 7. An integrated lead disk drivesuspension, including:a load beam having proximal and distal ends and abase region on the proximal end; a flexure including a spring region anda head bonding platform on the distal end of the load beam; and one ormore conductive traces integrated with and insulated from the flexureand load beam by an adhesive dielectric layer, the traces and adhesivedielectric layer extending between the head bonding platform and thebase region, and wherein portions of the conductive traces extendingbetween the distal end of the load beam and the head bonding platform atthe flexure are substantially free from the adhesive dielectric layer toreduce mechanical effects of the dielectric on spring characteristics ofthe flexure.
 8. An integrated lead disk drive suspension, including:aload beam having proximal and distal ends and a base region on theproximal end; a flexure having a head bonding platform on the distal endof the load beam; and one or more conductive traces integrated with andinsulated from the flexure and/or load beam by an adhesive dielectriclayer, the traces and adhesive dielectric layer extending between thehead bonding platform and the base region, the traces and adhesivedielectric layer each having a width, wherein the width of portions ofthe dielectric layer is about equal to or less than the width ofadjacent portions of the conductive traces.
 9. The integrated lead diskdrive suspension of claim 8 wherein the suspension includes at least twoconductive traces insulated from the flexure and load beam by theadhesive dielectric layer, and wherein the conductive traces andadhesive dielectric layer are parallel to and spaced-apart from oneanother.